PES studies of some short lived combustion intermediates
PES studies of some short lived combustion intermediates
A new multidetector photoelectron spectrometer has been used to study several short-lived molecules which are known to be important combustion intermediates. A detailed description of the instrument and in particular the problems associated with fluorine atom-molecule reactions are considered. Assignment of observed photoelectron spectra was achieved from experimental evidence and also with the aid of ab initio molecular orbital calculations performed on both the molecule and ion in each case. The first photoelectron bands of five alkyl radicals have been identified experimentally. The ethyl radical study suggested that the cation equilibrium geometry has a bridged structure whereas the cyclopropyl study indicated a cyclic cation structure with the α C-H lying in the carbon skeleton plane. Observation of both the n-propyl and isopropyl radicals led to estimates of the relative stabilities of the two cations. The neopentyl radical has also been studied. The first ionization energies of the isomeric hydroxymethly and methoxy radicals have been determined by photoelectron spectroscopy resulting in estimates of the relative energies of both neutral and cationic isomers in their ground electronic states. In addition, the first photoelectron band of two other oxygenated radicals, the methoxymethyl and oxiranyl radicals, have been observed experimentally. The gas phase reaction of fluorine atoms with benzene has been investigated. As a result the phenyl radical was observed via the abstraction reaction. The addition product, C_6H_6F, was also seen and this showed a kinetic isotope effect on deuteration. In addition, details of some mass spectrometric studies of methane combustion and calibration of the mass spectrometer for methyl radicals are presented. (D67262/86)
University of Southampton
1985
Ellis, Andrew Roderick
(1985)
PES studies of some short lived combustion intermediates.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
A new multidetector photoelectron spectrometer has been used to study several short-lived molecules which are known to be important combustion intermediates. A detailed description of the instrument and in particular the problems associated with fluorine atom-molecule reactions are considered. Assignment of observed photoelectron spectra was achieved from experimental evidence and also with the aid of ab initio molecular orbital calculations performed on both the molecule and ion in each case. The first photoelectron bands of five alkyl radicals have been identified experimentally. The ethyl radical study suggested that the cation equilibrium geometry has a bridged structure whereas the cyclopropyl study indicated a cyclic cation structure with the α C-H lying in the carbon skeleton plane. Observation of both the n-propyl and isopropyl radicals led to estimates of the relative stabilities of the two cations. The neopentyl radical has also been studied. The first ionization energies of the isomeric hydroxymethly and methoxy radicals have been determined by photoelectron spectroscopy resulting in estimates of the relative energies of both neutral and cationic isomers in their ground electronic states. In addition, the first photoelectron band of two other oxygenated radicals, the methoxymethyl and oxiranyl radicals, have been observed experimentally. The gas phase reaction of fluorine atoms with benzene has been investigated. As a result the phenyl radical was observed via the abstraction reaction. The addition product, C_6H_6F, was also seen and this showed a kinetic isotope effect on deuteration. In addition, details of some mass spectrometric studies of methane combustion and calibration of the mass spectrometer for methyl radicals are presented. (D67262/86)
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Published date: 1985
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Local EPrints ID: 461443
URI: http://eprints.soton.ac.uk/id/eprint/461443
PURE UUID: c42bc399-a4bf-4e25-916e-01984a3c4f3a
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Date deposited: 04 Jul 2022 18:46
Last modified: 04 Jul 2022 18:46
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Author:
Andrew Roderick Ellis
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